T-5 Transmission swaps

Feature Article from Hemmings Muscle Machines

One of the most versatile transmissions in the last 20 years or so has been the Borg-Warner T-5 manual transmission. This five-speed unit was used as original equipment by several manufacturers and can be easily adapted into older muscle cars as well. Based on the Borg Warner SR-4 and T-4 four-speed, a fifth gear was added to the case, creating the T-5. Actually, American Motors was the first manufacturer to use this transmission in the 1982 Spirit and Concord cars. Ford soon adopted the T-5, using this unit in the 1983 Mustangs and Thunderbirds. GM used the T-5 in the 1982 and up S/T series pickups and small Blazers, and their Astro vans. They began installing them in 1983 in the Camaros and Firebirds. Nissan also liked the idea of an internal shifter linkage five-speed, and they used this transmission in the 280ZX/300Z cars as well. Additionally, Honda and Isuzu used the T-5 in some models in the 1990s.
One of the advantages of this transmission is that the internal parts will interchange between versions of this unit. This enables you to select from several shift ratios, and the transmission is adaptable to different engine conversions or rear-end ratios. A T-5, while not known as a drag-racing transmission, can improve gas mileage in cars and trucks with taller gears because of the overdrive fifth-gear ratio. Another advantage is that the shifting linkages are internal, improving clearance for easier conversion because external shift linkage clearance is not an issue. The T-5 used in the GM models incorporates a hydraulic clutch master on the firewall and slave attached to the bell housing to provide smoother shifting with less effort than with a conventional mechanical clutch linkage. The Ford version of the T-5 uses a shift cable attached to the clutch pedal. The cases are all-aluminum and are referred to as toploaders because the access cover for the internals is on the top of the transmission rather than on the side like some other standard transmissions.
There were two generations of T-5 transmissions. All units used from beginning of production in 1982 until mid-1985 were referred to as "non-world class" or NWC. Non-world class versions had all-bronze synchro assemblies and used roller bearings to support the countershaft. In mid-1985, Ford began using the next generation T-5, called the "world class" or WC unit. These had numerous design improvements. First and second synchros were bearing and shaft assemblies rather than solid shafts in the non-world class, and the third and fourth synchro was a steel-reinforced unit with fiber-lined rings. Only fifth gear was still an all-bronze synchro. Both generation Ford T-5s used a 1-1/16-inch 10-spline input shaft diameter and a 28-spline output shaft. The 1983-92 GM T-5s that were coupled to V-8 engines have a 26-spline, 1-1/8-inch input shaft. The GM 4-cylinder and V-6 T-5s used the 3.52 through 4.03 ratios and were 1-inch, 14-spline input shafts. Later model F-Body world-class versions of the GM T-5s used the lower, 2.95 to 1 ratio gearbox and are the most sought-after for GM applications.
The non-world class T-5s were used in the following cars and trucks:
1982-85 AMC Spirit, Eagle, Concord
1982-96 Jeep CJ and XJ trucks
1982-85 Ford Mustang, Thunderbird
1983-87 Camaro, Firebird
1982-92 Chevy S/T-10 pickups, Blazers, Astro van
1982-83 Nissan 280ZX
1984-86 Nissan 300ZX
1984-86 Chevette and Pontiac T-1000 also used this unit; however, the countershaft bearings were smaller and the T-Body bellhousing was not interchangeable with any other GM models.
The more popular world-class units were used in these original vehicles:
Late 1985-96 Mustang/Cougar/Thunderbird
1988-96 Camaro and Firebird
1993-95 Chevy/GMC S/T series trucks
1994-96 Honda Passport
1991-97 Isuzu Rodeo
Note: 4-cylinder Ford 2.3-liter Turbo units as well as 1993-96 Cobra "Z-Spec" T-5s do not interchange directly, due to a difference in the input shaft bearings. The most important difference between the non-world class and the world-class transmissions is the torque rating. Later is better (or the higher the tag number). For example, 1983-89 Mustang units, both world class and non-world class, were rated at 265-lbs.ft. of torque. The 1990-93 versions were rated at 300-lbs.ft., and the 1993-96 Cobra "Z-Spec" T-5 was rated at 330-lbs.ft.
You should be looking for as complete a unit as possible, when searching the swap meets or salvage yards for these transmissions. On GM's crossmember, clutch master, clutch hose, and clutch slave cylinder should come with the unit to save time and plumbing. It would be even better if the starter and flywheel were still with the car; usually later-model starters are lighter and have higher torque. If converting from an automatic-equipped car to a manual, a clutch pedal from the donor car will also be needed, as well as the bellhousing. On Ford vehicles, hydraulics are not used, and a shift cable is employed in place of the clutch master and slave cylinders. Make sure to take this cable when buying parts off the donor car. Aftermarket clutch cables and crossmembers are available, if these parts cannot be found.
An identification tag number, which is on one of the mounting bolts on the tail case, can identify all T-5 manual 5-speeds. They all start with prefix 1352, and the next few digits will tell you what the unit came out of originally and what its shift ratio is. You can check any original tag number online at www.5speeds.com. Numbering series starts at 001 and runs as high as about 260. Borg-Warner sold the rights to the T-5 to Tremec in the late 1990s; however, there is no difference between the two manufacturers' production units, other than the name used in the castings.
Ratios depend on tag number, but most are in the 3.35 to 3.97:1 range. There are 2.95:1 units that were used in the late-model Mustangs, Camaros and Firebirds. The 2.3 Turbo Fords used a few units that were 4.06:1. Speedometer drive gears were 6, 7 or 8 teeth, but may have to be changed, depending on engine and rear-end size in the transplant vehicle. Changing of the speedometer gear is a definite requirement when installing a transmission and V-8 unit in a 6-cylinder, and vice versa.
The Ford versions of the T-5 will adapt easily to the earlier Ford three- and four-speed manual bellhousings by an adapter plate which enlarges the metric mounting bosses to 1/2-inch diameter, and adds 3/4-inch in spacing. Installation of a T-5 into an earlier Ford product is fairly easy, because of the bellhousing similarities. You should make sure, however, that the proper flywheel is used, depending on the year of your engine. The 1981 and earlier Ford small-blocks used a 28-ounce imbalance, 157-tooth flywheel. Any of the small-block Fords newer than 1981 used a 50-ounce imbalance, 157-tooth flywheel. These should not be interchanged. Late-model T-5 bellhousings used on earlier Ford V-8 engines will bolt up, but the late-model fulcrum for the fork needs to be replaced with an early-style fulcrum installed on the inside of the housing to align the throw-out bearing fork. You can, of course, also use an aftermarket scatter shield for this changeover, eliminating these adapters.
Because of the similarities in earlier and later Ford small-block bellhousings, it's possible your acquired T-5, with an early flywheel, will fit in these small-block V-8 applications:
1965-68 Ford full-size cars
1965-69 Comet
1967-70 Fairlane
1967-70 Falcon
1968-73 Mustang
1971-74 Torino
1970-74 Montego
Mounting a T-5 in place of a Super T-10, Muncie or Saginaw into a Chevy is pretty straightforward; the input shaft length is identical, and the whole unit is only two inches longer overall at the transmission mount pad. A shorter driveshaft would be required, and modifications to the crossmember would be necessary to mount the T-5 properly. The bellhousing-to-block bolt patterns are the same on the earlier V-8s, and the bellhousing-to-transmission configuration is common to all other GM manual transmissions; so installation of a 1983-92 GM T-5 out of a V-8 should be relatively painless, if you can acquire all the necessary parts from the donor car. Although the V-6 and 4-cylinder input shafts are 14-spline and will fit with the proper clutch disc, they are not recommended for V-8 applications. They do not have the higher torque ratings required for the V-8 units without upgrading the internals. Installing one of these five-speeds in a Buick, Pontiac or Oldsmobile would require the use of the proper B-O-P bellhousing. There are two that have been found to fit both engine and transmission. One is out of a 1979-81 Firebird or 1979 Skylark (casting number 563441). The other is from a 1982 F-body (casting number 14037657).
All 1993 and up GM cars with the T-5 used the Ford bellhousing bolt pattern, and not the earlier GM pattern. The 1993 and up GM applications were limited to V-6 Camaros/Firebirds, as the option was not offered in the V-8s. You can identify these transmissions by the 26-spline GM input shaft with a Ford bolt pattern. You should also know that F-Body bellhousings mount the transmission at a 17-degree angle towards the driver, which could cause problems when trying to line up and mount the shifter through the floorboards of other models.
Aftermarket adapters to mount the Ford T-5 are available for AMC V-8s, Ford flatheads, and early 1950s Chrysler Hemis. Adapters for GM T-5s are also available for these same cars, plus Buick V-6 and Chrysler flathead 6-cylinder. A, B, and E-Body Mopars can also use the T-5 with an aftermarket bellhousing from one of several suppliers. AMC and Jeep can replace their existing SR4 or T-4 unit with the T-5, and adapters are available to install it in 4WD Jeep applications too. There are numerous "How To" installation instructions on Internet web forums from various enthusiast groups that include Imports and early Chevrolet six-cylinder truck applications.
T-5s are currently selling for between $150 and $500 through swap meets and salvage yards, and complete changeover kits are being sold in the $850 range. Rebuilt T-5s run about $700 to $850. The improvements in performance gained by changing to a T-5 will certainly outweigh the effort required to complete this installation, and the fuel savings, as an added bonus, will help make the decision to upgrade to this transmission one to consider.

This article originally appeared in the July, 2004 issue of Hemmings Muscle Machines.